Fusion splicing device and fusion splicing method

Abstract

A fusion splicer (1) according to one embodiment comprises: a base (12) having a first groove (13) that positions an optical fiber (F); and a clamp (20) having a second groove (21) into which the optical fiber (F) placed in the first groove (13) enters, and a pressing part (34) that presses the optical fiber (F) that has entered the second groove (21). The base (12) and the clamp (20) have an entrance part (31) which is a portion formed by the first groove (13) and the second groove (21) and into which the optical fiber (F) is inserted; and a fiber hole (33) which is formed by the first groove (13) and the second groove (21) and extends from the entrance part (31) in the insertion direction in which the optical fiber (F) is inserted. The pressing part (34) is positioned at a location toward the insertion direction from the fiber hole (33). The cross-sections of the entrance part (31) and the fiber hole (33), which are cut along a plane orthogonal to the insertion direction, are circular. The inner diameter of the end part of the fiber hole (33) opposite to the entrance part (31) is smaller than the inner diameter of the entrance part (31) and equal to or smaller than the outer diameter of the optical fiber (F).

Description

Fusion Splicing Machine and Fusion Splicing Method

[0001] The present disclosure relates to a fusion splicing machine and a fusion splicing method. This application claims priority based on Japanese Application No. 2024-172710 filed on October 1, 2024, and incorporates all the descriptions described in the said Japanese application.

[0002] Patent Document 1 describes a fusion splicing machine. The fusion splicing machine includes a base in which a V-groove is formed, and a plurality of clamps for pressing each of the plurality of optical fibers placed in the V-groove. The plurality of clamps are arranged along the direction in which the plurality of optical fibers are arranged. Each of the plurality of clamps presses the optical fiber corresponding to each clamp.

[0003] Patent Document 2 describes an optical fiber ribbon core wire. In a cross section perpendicular to the longitudinal direction of the optical fiber ribbon core wire, the cores of all the multi-core fibers are arranged in the same manner as each other. The optical fiber ribbon core wire is such that the multi-core fibers are intermittently adhered by an adhesive portion at a predetermined interval in the longitudinal direction.

[0004] International Publication No. 2023 / 120480, Japanese Unexamined Patent Publication No. 2017-173514

[0005] The fusion splicing machine according to the present disclosure includes a base having a first groove for positioning an optical fiber, a second groove into which the optical fiber placed in the first groove enters, and a clamp having a pressing portion for pressing the optical fiber that has entered the second groove. The base and the clamp are formed by the first groove and the second groove, and have an entrance portion that is a portion where the optical fiber is inserted, and a fiber hole that is formed by the first groove and the second groove and extends from the entrance portion in the insertion direction, which is the direction in which the optical fiber is inserted. The pressing portion is located at a position in the insertion direction from the fiber hole. The cross sections of the entrance portion and the fiber hole cut along a plane perpendicular to the insertion direction are circular. The inner diameter of the end portion of the fiber hole opposite to the entrance portion is smaller than the inner diameter of the entrance portion and is not more than the outer diameter of the optical fiber.

[0006] Figure 1 is a perspective view showing a fusion splicer according to an embodiment. Figure 2 is a perspective view showing the fusion splicer of Figure 1 with the windbreak cover open. Figure 3 is a cross-sectional perspective view showing the base, clamp, and optical fiber of the fusion splicer of Figure 1. Figure 4 is a side view showing the base and clamp of Figure 3. Figure 5 is a side view showing the base and clamp viewed from the opposite direction to Figure 4. Figure 6 is a schematic diagram showing the insertion of an optical fiber into the base and clamp. Figure 7 is a schematic diagram showing the entrance, fiber hole, and retaining portion of the base and clamp. Figure 8 is a flowchart showing an example of the steps of the fusion splicing method according to an embodiment. Figure 9 is a diagram showing the first groove and second groove according to a modified example. Figure 10 is a diagram showing the first groove and second groove according to a modified example.

[0007] Incidentally, optical fibers can rotate when they are held in place by a clamp. If an optical fiber that requires rotational alignment rotates due to the clamp, the position of the optical fiber core may shift due to the rotation, potentially causing connection loss in the fusion spliced ​​optical fiber. Therefore, it is necessary to avoid rotating the optical fiber before fusion splicing.

[0008] The purpose of this disclosure is to provide a fusion splicer and a fusion splicing method that can prevent the rotation of optical fibers before fusion splicing.

[0009] According to this disclosure, rotation of the optical fiber before fusion splicing can be prevented.

[0010] First, embodiments of the fusion splicer and fusion splicing method according to this disclosure will be listed and described. (1) The fusion splicer according to this embodiment comprises a base having a first groove for positioning an optical fiber, a clamp having a second groove into which the optical fiber placed in the first groove enters, and a pressing portion for holding the optical fiber that has entered the second groove. The base and the clamp have an entrance portion formed by the first groove and the second groove, which is the portion into which the optical fiber is inserted, and a fiber hole formed by the first groove and the second groove, which extends from the entrance portion in the insertion direction, which is the direction in which the optical fiber is inserted. The pressing portion is located in the insertion direction from the fiber hole. The cross-sections of the entrance portion and the fiber hole, cut along a plane perpendicular to the insertion direction, are circular in shape. The inner diameter of the end of the fiber hole opposite the entrance portion is smaller than the inner diameter of the entrance portion and is less than or equal to the outer diameter of the optical fiber.

[0011] In this fusion splicer, the base has a first groove for positioning the optical fiber, and the clamp has a second groove and a retaining portion. The base and clamp have an entrance portion formed by the first and second grooves, into which the optical fiber is inserted, and a fiber hole formed by the first and second grooves, extending from the entrance portion in the insertion direction. The retaining portion is located in the direction of insertion from the fiber hole. The cross-sections of the entrance portion and the fiber hole, cut along a plane perpendicular to the insertion direction, are circular. The inner diameter of the end of the fiber hole opposite the entrance portion is smaller than the inner diameter of the entrance portion. When the optical fiber is inserted into the fiber hole from the entrance portion, the optical fiber passes through the circular cross-section of the fiber hole to reach the retaining portion, thus preventing the optical fiber from rotating until it reaches the retaining portion. Because the cross-section of the fiber hole is circular, the optical fiber receives a force toward the center of the optical fiber as it passes through the fiber hole, thus preventing the optical fiber from rotating. This prevents the position of the optical fiber core from shifting due to rotation, thereby reducing connection loss in the optical fiber after fusion splicing.

[0012] (2) In (1) above, the fiber hole may have a tapered portion, which is the part where the inner diameter of the fiber hole decreases as it moves away from the entrance. In this case, when the optical fiber is inserted into the entrance and the optical fiber is inserted into the fiber hole, a force toward the center of the optical fiber can be applied to the optical fiber in the tapered portion. Therefore, rotation of the optical fiber can be prevented more reliably.

[0013] (3) In (1) or (2) above, the fiber hole may have a straight section in which the inner diameter of the fiber hole is constant along the insertion direction. In this case, the optical fiber can be smoothly inserted along the straight section.

[0014] (4) In any of (1) to (3) above, the end of the base opposite to the insertion direction may be located further in the opposite direction than the end of the clamp in the opposite direction. In this case, since the base protrudes further in the opposite direction than the clamp, the optical fiber can be smoothly inserted from the first groove of the base into the fiber hole.

[0015] (5) In any of (1) to (4) above, the cross-section of the portion including the retaining part, cut along a plane perpendicular to the insertion direction, may be circular. In this case, the circular cross-section of the portion including the retaining part prevents the optical fiber from rotating when it reaches the retaining part.

[0016] (6) In any of (1) to (5) above, the retaining portion may be provided at the exit portion, which is the part where the optical fiber exits the first groove and the second groove. In this case, by providing the retaining portion at the exit portion, the optical fiber can be securely held at the exit portion.

[0017] (7) The fusion splicing method according to this embodiment fusion splices optical fibers using the fusion splicer described above. The fusion splicing method comprises the steps of lowering a clamp onto a base so that the second groove is positioned above the first groove, inserting an optical fiber into the fiber hole from the entrance after lowering the clamp onto the base, and holding the optical fiber with a retaining part located in the direction of insertion from the fiber hole.

[0018] In this fusion splicing method, after lowering the clamp onto the base so that the second groove is positioned above the first groove, the optical fiber is inserted into the fiber hole formed by the first and second grooves. The inner diameter of the end of the fiber hole opposite the entrance is smaller than the inner diameter of the entrance. By inserting the optical fiber into this fiber hole after the clamp is lowered, the force on the optical fiber before it reaches the clamping portion can be reduced. Therefore, rotation of the optical fiber before fusion splicing can be prevented.

[0019] Specific examples of fusion splicers and fusion splicing methods according to the embodiments of this disclosure will be described below with reference to the drawings. In the description of the drawings, the same or corresponding elements are denoted by the same reference numerals, and redundant explanations are omitted as appropriate. For the sake of ease of understanding, some parts of the drawings may be simplified or exaggerated, and the dimensional ratios, etc., are not limited to those indicated in the drawings.

[0020] Figure 1 is a perspective view showing a fusion splicer 1 according to an embodiment. The fusion splicer 1 has a windbreak cover 2 on its upper part. Figure 2 is a perspective view showing the fusion splicer 1 with the windbreak cover 2 open. As shown in Figures 1 and 2, the fusion splicer 1 includes a housing 3. The fusion splicer 1 includes a fusion splicing section 4 for fusing optical fibers together, and a heater 5 for heating and shrinking a fiber reinforcement sleeve that is placed over the connection of the optical fibers fused in the fusion splicing section 4. The fusion splicer 1 includes a monitor 7 that displays the state of the fusion splice between optical fibers as captured by a microscope (not shown) located inside the housing 3. The fusion splicer 1 includes a power switch 8 for switching the power of the fusion splicer 1 on and off, and a connection start switch 9 for performing the fusion splice of optical fibers.

[0021] The fusion splicer 4 comprises a pair of discharge electrodes 6 for fusion splicing multiple optical fibers together, and a pair of optical fiber holders 10 for holding multiple optical fibers. For example, the fusion splicer 1 fusion splices multiple optical fibers together with multiple other optical fibers. The pair of discharge electrodes 6 fuses multiple optical fibers together by discharge. The discharge electrodes 6 and the optical fiber holders 10 are aligned along the Z-axis direction. The Z-axis direction is the direction in which each of the multiple optical fibers to be fusion spliced ​​extends.

[0022] Figure 3 is a cross-sectional perspective view showing the area around the discharge electrode 6 in the fusion splicer 1. As shown in Figures 2 and 3, the fusion splicer 1 includes a base 12 on which a plurality of optical fibers F to be fusion spliced ​​are placed, and clamps 20 for holding the optical fibers F placed on the base 12. Each of the plurality of optical fibers F is an optical fiber that requires rotational alignment in the fusion splicer 1. Optical fibers that require rotational alignment are, for example, multi-core fibers (MCF), polarization-maintaining fibers (PMF), or hollow-core fibers (HCF).

[0023] The clamp 20 holds, for example, an optical fiber F (for example, the glass portion of the optical fiber F, which is a glass fiber). However, the clamp 20 may also hold the coating portion of the optical fiber F that covers the glass portion of the optical fiber F. Furthermore, the clamp 20 may hold both the glass portion and the coating of the optical fiber F. The base 12 has a main surface 12b on which a plurality of optical fibers F are placed. On the main surface 12b, the plurality of optical fibers F are arranged along the X-axis direction which intersects the Z-axis direction. For example, the X-axis direction is an in-plane direction of the main surface 12b and is perpendicular to the Z-axis direction. A pair of discharge electrodes 6 are positioned on each side of the X-axis direction as viewed from the plurality of optical fibers F.

[0024] The clamp 20 moves along the Y-axis, which intersects both the X-axis and Z-axis directions. The Y-axis is the direction in which the clamp 20 approaches the base 12. Hereinafter, the Y-axis direction may be referred to as down, lower side, or downward, and the direction opposite to the Y-axis direction may be referred to as up, upper side, or upward. However, these are directions for the sake of explanation and do not limit the position or direction of the object.

[0025] Figure 3 shows an example where one clamp 20 is provided. However, the fusion splicer 1 may have multiple clamps 20. In this case, the multiple clamps 20 may be arranged along the X-axis direction, which is the direction in which the multiple optical fibers F are aligned. For example, the clamps 20 include a low-friction material. As an example, the clamps 20 are made of zirconia. In this case, even if the multiple clamps 20 come into contact with each other, the sliding properties of the clamps 20 can be ensured.

[0026] For example, the multiple clamps 20 may be independent of each other, or each of the independent clamps 20 may hold down an optical fiber F. In this case, since each of the multiple clamps 20 holds down an optical fiber F individually, it is possible to apply pressure according to each optical fiber F. The effect of the clamps 20 on the optical fiber F can be made less likely to affect other optical fibers F. Even if there is debris or dust on the base 12, the effect of such debris or dust can be made less likely to affect the multiple optical fibers F, so that the multiple optical fibers F can be properly held down. Therefore, the axial misalignment of the optical fibers F can be reduced.

[0027] For example, the fusion splicer 1 includes a support member 40 that supports the clamp 20. The support member 40 has a support portion 41 that supports the clamp 20 and a head portion 42 provided above the support portion 41. The upper part of the support portion 41 fits into the head portion 42. The support member 40 has a spring (not shown) located between the upper end of the support portion 41 and the inner surface of the head portion 42. This spring is expandable and contractible along the Y-axis. This spring allows the support portion 41 to move along the Y-axis relative to the head portion 42. The clamp 20 supported by the support portion 41 is movable along the Y-axis relative to the base 12.

[0028] Figure 4 is a side view showing the base 12 and clamp 20 as viewed along the Z-axis direction. Figure 5 is a side view showing the base 12 and clamp 20 as viewed in the direction opposite to the Z-axis direction. The base 12 has a first groove 13 for positioning the optical fiber F. The optical fiber F is not shown in Figures 4 and 5. The clamp 20 has a second groove 21 into which the optical fiber F placed in the first groove 13 enters. The base 12 and clamp 20 have an entrance portion 31 into which the optical fiber F is inserted into the first groove 13 and the second groove 21, and an exit portion 32 into which the optical fiber F exits from the first groove 13 and the second groove 21.

[0029] The first groove 13 extends along the Z-axis direction. The base 12 has, for example, a plurality of first grooves 13. The plurality of first grooves 13 are aligned along the X-axis direction. When viewed along the Z-axis direction, the shape of the first groove 13 is arc-shaped. The second groove 21 extends along the Z-axis direction. The clamp 20 has, for example, a plurality of second grooves 21. The plurality of second grooves 21 are aligned along the X-axis direction. When viewed along the Z-axis direction, the shape of the second groove 21 is arc-shaped.

[0030] The curvature of the second groove 21 matches the curvature of the first groove 13, and the second groove 21 is superimposed on the first groove 13. When viewed along the Z-axis direction, the shapes of the first groove 13 and the second groove 21 are circular. "Circular shape" means, for example, a perfect circle. However, "circular shape" may include not only perfect circles but also ellipses that are longer than a perfect circle by the amount of tolerance, or other shapes that differ from a perfect circle to the extent that tolerance is present. The entrance portion 31 is formed by the first groove 13 and the second groove 21. The entrance portion 31 is located at the end of the base 12 and clamp 20 in the direction opposite to the Z-axis direction. The exit portion 32 is formed by the first groove 13 and the second groove 21. The exit portion 32 is located at the end of the base 12 and clamp 20 in the Z-axis direction.

[0031] Figure 6 is a schematic diagram showing the state before and after the optical fiber F is inserted into the inlet portion 31. As shown in Figures 4, 5, and 6, the base 12 and clamp 20 have a fiber hole 33 extending from the inlet portion 31 in the insertion direction D, which is the direction in which the optical fiber F is inserted. In this embodiment, the insertion direction D coincides with the Z-axis direction. The cross-sections of the inlet portion 31 and the fiber hole 33, cut along a plane perpendicular to the insertion direction D, are circular. For example, the cross-section of the outlet portion 32, cut along a plane perpendicular to the insertion direction D, is circular. The fiber hole 33 is formed by a first groove 13 and a second groove 21. For example, an optical fiber F held in an optical fiber holder 10 placed on a fiber holder base 14 is inserted into the fiber hole 33.

[0032] The clamp 20 has a retaining portion 34 that holds the optical fiber F inserted into the second groove 21. The retaining portion 34 is the part that holds the optical fiber F that has been passed through the fiber hole 33. The retaining portion 34 is located in the insertion direction D from the fiber hole 33. For example, the retaining portion 34 is provided at the exit portion 32. However, the retaining portion 34 may be provided at a location other than the exit portion 32, for example, between the entrance portion 31 and the exit portion 32. For example, the cross-section of the portion including the retaining portion 34 when cut along a plane perpendicular to the insertion direction D is circular.

[0033] For example, the end 12c of the base 12 in the direction opposite to the insertion direction D coincides with the end 20c of the clamp 20 in the opposite direction. However, as shown in Figure 7, the end 12c of the base 12 may be located further in the direction opposite to the insertion direction D than the end 20c of the clamp 20. Figure 7 is a schematic diagram showing the fiber hole 33 and the retaining portion 34. The end 12c of the base 12 may protrude in the opposite direction than the end 20c of the clamp 20. In this case, the first groove 13 includes a guide groove 13b extending from the entrance portion 31 in the opposite direction. The optical fiber F can be smoothly inserted from the guide groove 13b into the fiber hole 33.

[0034] As described above, the cross-section of the fiber hole 33 cut along a plane perpendicular to the insertion direction D is circular, and for example, the inner diameter of the fiber hole 33 decreases from the entrance portion 31 toward the retaining portion 34. The inner diameter of the end of the fiber hole 33 opposite the entrance portion 31 is smaller than the inner diameter of the entrance portion 31 and is less than or equal to the outer diameter of the optical fiber F. The end of the fiber hole 33 opposite the entrance portion 31 is, for example, the portion that includes the retaining portion 34. Because the inner diameter of the end of the fiber hole 33 opposite the entrance portion 31 is less than or equal to the outer diameter of the optical fiber F, the retaining portion 34 can hold the optical fiber F.

[0035] For example, the fiber hole 33 does not have any steps. In this case, the optical fiber F can be inserted into the fiber hole 33 smoothly. For example, the fiber hole 33 has a tapered portion 33b, which is the part where the inner diameter of the fiber hole 33 decreases as it moves away from the entrance portion 31, and a straight portion 33c, in which the inner diameter of the fiber hole 33 is constant along the insertion direction D. For example, the tapered portion 33b extends from the entrance portion 31 in the insertion direction D, and the straight portion 33c extends from the end of the tapered portion 33b opposite to the entrance portion 31 in the insertion direction D. For example, a portion including a retaining portion 34 (exit portion 32) is provided at the end of the straight portion 33c in the insertion direction D. In this case, the inner diameter of the straight portion 33c is the same as the inner diameter of the portion including the retaining portion 34 (exit portion 32).

[0036] In the above example, the tapered portion 33b and the straight portion 33c are arranged in this order along the insertion direction D. However, the positions of the tapered portion 33b and the straight portion 33c are not limited to the above example. For example, the straight portion 33c may extend from the inlet portion 31, and the tapered portion 33b may extend in the insertion direction D from the end of the straight portion 33c in the insertion direction D. The tapered portion 33b may extend to a portion including the retaining portion 34 (for example, the outlet portion 32). The fiber hole 33 may have only the tapered portion 33b.

[0037] The fusion splicing method according to this embodiment will be described with reference to Figure 8. Figure 8 is a flowchart showing an example of a method for performing fusion splicing on multiple optical fibers F. Below, an example of a method for fusion splicing multiple optical fibers F using the fusion splicer 1 described above will be explained.

[0038] Step S1 involves placing the optical fiber F in the optical fiber holder 10. For example, the optical fiber F is held in the optical fiber holder 10 which is placed on the fiber holder base 14. The clamp 20 is lowered onto the base 12 (step S2, step of lowering the clamp). At this time, the clamp 20 is lowered onto the base 12 so that the second groove 21 is positioned above the first groove 13. Step S3 involves placing the optical fiber holder 10 that holds the optical fiber F in the fusion splicer 1. Step S2 does not have to be performed after step S1 and before step S3; it may be performed before step S1 or after step S3.

[0039] After lowering the clamp 20 onto the base 12 and installing the optical fiber holder 10 on the fusion splicer 1, the optical fiber holder 10 is moved to insert the optical fiber F into the fiber hole 33 from the entrance 31 (step S4, step of inserting the optical fiber). The optical fiber F is held in place by the retaining portion 34 located in the insertion direction D from the fiber hole 33 (step of holding the optical fiber). For example, the optical fiber F is held in place by the retaining portion 34 when it enters the portion including the retaining portion 34, which has a radius of curvature less than or equal to the outer radius of the optical fiber F. At this time, the optical fiber F protrudes from the exit portion 32 to the outside of the base 12 and clamp 20. If the radius of curvature of the portion including the retaining portion 34 is smaller than the outer radius of the optical fiber F, when the optical fiber F enters the portion including the retaining portion 34, the clamp 20 moves upward against the biasing force of the spring of the support member 40, as described above, causing the optical fiber F to enter the portion including the retaining portion 34.

[0040] Fusion splicing is performed by discharging and heating a plurality of optical fibers F with a pair of discharge electrodes 6. At this time, a pair of optical fibers F aligned along the Z-axis are fused together (step S5). After the above steps, the series of steps of the fusion splicing method is completed.

[0041] The effects and advantages obtained from the fusion splicer 1 and fusion splicing method according to this embodiment will be described. In the fusion splicer 1, the base 12 has a first groove 13 for positioning the optical fiber F, and the clamp 20 has a second groove 21 and a retaining portion 34. The base 12 and clamp 20 have an entrance portion 31 into which the optical fiber F is inserted into the first groove 13 and the second groove 21, and a fiber hole 33 extending from the entrance portion 31 in the insertion direction D. The retaining portion 34 is located in the insertion direction D from the fiber hole 33. When cut along a plane perpendicular to the insertion direction D, the cross-sections of the entrance portion 31 and the fiber hole 33 are circular. The inner diameter of the end of the fiber hole 33 opposite to the entrance portion 31 is smaller than the inner diameter of the entrance portion 31. When the optical fiber F is inserted into the fiber hole 33 from the entrance portion 31, the optical fiber F passes through the circular cross-section fiber hole 33 to reach the retaining portion 34, thus preventing rotation of the optical fiber F from passing through the fiber hole 33 to reaching the retaining portion 34. Because the cross-section of the fiber hole 33 is circular, when the optical fiber F passes through the fiber hole 33, the optical fiber F is subjected to a force directed toward the center of the optical fiber F, thus preventing rotation of the optical fiber F. By preventing displacement of the core of the optical fiber F due to rotation, connection loss occurring in the optical fiber F after fusion splicing can be reduced.

[0042] The fiber hole 33 may have a tapered portion 33b, which is the part where the inner diameter of the fiber hole 33 decreases as it moves away from the entrance portion 31. In this case, when the optical fiber F is inserted into the entrance portion 31 and the optical fiber F is inserted into the fiber hole 33, a force toward the center of the optical fiber F can be applied to the optical fiber F at the tapered portion 33b. Therefore, rotation of the optical fiber F can be prevented more reliably. The fiber hole 33 may also have a straight portion 33c, where the inner diameter of the fiber hole 33 is constant along the insertion direction D. In this case, the optical fiber F can be smoothly inserted along the straight portion 33c.

[0043] The end portion 12c of the base 12 in the direction opposite to the insertion direction D may be located at a position further in the opposite direction than the end portion 20c of the clamp 20 in the opposite direction. In this case, since the base 12 protrudes in the direction opposite to the insertion direction D more than the clamp 20, the optical fiber F can be smoothly inserted from the first groove 13 (for example, the guiding groove 13b) of the base 12 into the fiber hole 33.

[0044] The cross-section of the portion including the pressing portion 34 when cut along a plane orthogonal to the insertion direction D may be circular. In this case, since the cross-sectional shape of the portion including the pressing portion 34 is circular, the rotation of the optical fiber F reaching the pressing portion 34 can be prevented.

[0045] The pressing portion 34 may be provided at the outlet portion 32 which is the portion where the optical fiber F exits from the first groove 13 and the second groove 21. In this case, since the pressing portion 34 is provided at the outlet portion 32, the optical fiber F can be reliably pressed at the outlet portion 32.

[0046] In the fusion splicing method according to the present embodiment, after lowering the clamp 20 onto the base 12 such that the second groove 21 is positioned above the first groove 13, the optical fiber F is inserted into the fiber hole 33 formed by the first groove 13 and the second groove 21, and the inner diameter of the end portion opposite to the inlet portion 31 of the fiber hole 33 is smaller than the inner diameter of the inlet portion 31. Therefore, when the optical fiber F is inserted into the fiber hole 33 after the clamp 20 is lowered, the force applied to the optical fiber F before reaching the pressing portion 34 can be reduced. Thus, the rotation of the optical fiber F before fusion splicing can be prevented.

[0047] As described above, embodiments of the fusion splicer and the fusion splicing method according to the present disclosure have been explained. However, the fusion splicer and the fusion splicing method according to the present disclosure are not limited to the above-described embodiments, and may be modified within the scope of the gist described in the claims without changing the gist. That is, the shape, size, material, number, and arrangement mode of each part of the fusion splicer, as well as the content and order of the steps of the fusion splicing method, can be appropriately changed within the scope of the above gist.

[0048] For example, in the above-described embodiment, an example where the cross-section of the portion including the pressing portion 34 cut along a plane orthogonal to the insertion direction D is circular has been described. However, the cross-section of the portion including the pressing portion 34 does not have to be circular. FIGS. 9 and 10 are diagrams showing various examples of the pressing portion. (1) of FIG. 9 shows the pressing portion 34 which is a part of the cross-section formed by the above-described first groove 13 and second groove 21 and has a circular shape.

[0049] As shown in (2) of FIG. 9, the fusion splicer may include a clamp 20B having a second groove 21B with a radius of curvature smaller than the outer radius of the optical fiber F, instead of the clamp 20. In this case, the end portion of the second groove 21B becomes the pressing portion 34B, and the pressing portion 34B contacts the optical fiber F. In order to prevent wear of the optical fiber F, the pressing portion 34B may be chamfered. As shown in (3) of FIG. 9, the fusion splicer 1 may include a base 12C having a first groove 13C with a radius of curvature smaller than the outer radius of the optical fiber F, instead of the base 12. In this case, since the optical fiber F contacts the end portion 13x of the first groove 13C, this portion 13x may be chamfered in order to prevent wear of the optical fiber F.

[0050] As shown in (1) of FIG. 10, the shapes of the first groove 13j and the second groove 21j in the cross-section cut along a plane orthogonal to the insertion direction D do not have to be arc-shaped. The fusion splicer may include a base 12D having a first groove 13j with an elliptical arc-shaped cross-section and a clamp 20D having a second groove 21j with an elliptical arc-shaped cross-section, instead of the base 12 and the clamp 20. In this case, the cross-sectional shape of the pressing portion 34D is a part of an elliptical shape.

[0051] Only the cross-section of either the first groove or the second groove may be elliptical arc-shaped. Figure 10(2) shows an example in which only the base 12D has an elliptical arc-shaped first groove 13j. In this case, the inner surface of the second groove 21 becomes the pressing portion 34E. Unlike this example, only the clamp may have an elliptical arc-shaped second groove. As shown in Figure 10(3), the fusion splicer comprises the aforementioned base 12D and clamp 20B, and the pressing portion 34B may be chamfered. In summary, the shapes of the first groove, the second groove and the pressing portion can be changed as appropriate. The shape of the outlet portion is also not limited to the shape of the outlet portion 32 described above and can be changed as appropriate.

[0052] 1...Fusion splicer 2...Windshield cover 3...Housing 4...Fusion splice section 5...Heating unit 6...Discharge electrode 7...Monitor 8...Power switch 9...Connection start switch 10...Optical fiber holder 12, 12C, 12D...Base 12b...Main surface 12c...End 13, 13C, 13j...First groove 13b...Guiding groove 13x...Part 14...Fiber holder base 20, 20B, 20D...Clamp 20c...End 21, 21B, 21j...Second groove 31...Inlet 32...Outlet 33...Fiber hole 33b...Tapered section 33c...Straight section 34, 34B, 34D, 34E...Pressing section 40...Support member 41...Support section 42...Head section F...Optical fiber

Claims

1. A fusion splicer comprising: a base having a first groove for positioning an optical fiber; a clamp having a second groove into which the optical fiber placed in the first groove enters, and a pressing portion for holding the optical fiber that has entered the second groove, wherein the base and the clamp have an entrance portion formed by the first groove and the second groove, into which the optical fiber is inserted; a fiber hole formed by the first groove and the second groove, extending from the entrance portion in the insertion direction, which is the direction in which the optical fiber is inserted, wherein the pressing portion is located in the insertion direction from the fiber hole, the cross-sections of the entrance portion and the fiber hole cut along a plane perpendicular to the insertion direction are circular, and the inner diameter of the end of the fiber hole opposite the entrance portion is smaller than the inner diameter of the entrance portion and is less than or equal to the outer diameter of the optical fiber.

2. The fusion splicer according to claim 1, wherein the fiber hole has a tapered portion, which is a portion where the inner diameter of the fiber hole decreases as it moves away from the entrance portion.

3. The fusion splicer according to claim 1 or claim 2, wherein the fiber hole has a straight portion along the insertion direction in which the inner diameter of the fiber hole is constant.

4. The fusion splicer according to any one of claims 1 to 3, wherein the end of the base in the direction opposite to the insertion direction is located in a position opposite to the opposite end of the clamp.

5. The fusion splicer according to any one of claims 1 to 4, wherein the cross-section of the portion including the pressing portion, cut along a plane perpendicular to the insertion direction, is circular in shape.

6. The fusion splicer according to any one of claims 1 to 5, wherein the retaining portion is provided at the exit portion which is the portion in which the optical fiber exits the first groove and the second groove.

7. A fusion splicing method for fusion splicing optical fibers using a fusion splicer according to any one of claims 1 to 6, comprising: lowering the clamp onto the base such that the second groove is positioned above the first groove; inserting the optical fiber into the fiber hole from the entrance after lowering the clamp onto the base; and holding the optical fiber with the retaining portion located in the insertion direction from the fiber hole.

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